Thousands more wind turbines could be built on currently blocked sites when new “stealth” technology trialled in East Anglia becomes available next year.

Thousands more wind turbines could be built on currently blocked sites when new “stealth” technology trialled in East Anglia becomes available next year.

Across the UK, 5,000 turbines are currently on hold following objections from military and civil aviation authorities because they can interfere with important radar signals.

But, following “successful” trials in Norfolk last year, a seven figure scheme to develop new “stealth” turbines that ease the problem is well under way, which could reopen the door for many of the stalled bids, some of which apply to this county.

Dr Dave Moore is business lead for the scheme for defence technology specialists QinetiQ, who are working with turbine suppliers Vestas.

“At the moment 5,000 turbines are blocked because of this issue and it is increasing. It is a major threat to the UK being able to meet its renewable energy targets by 2020,” said Dr Moore, who is from Norfolk.

The UK is said to be the windiest country in Europe and the government wants 15pc of our energy needs to be met by renewable green sources - the lion's share of which is expected to come from wind - by 2020.

Currently this country has about 4GW, both onshore and offshore, of installed capacity but is estimated to need 33GW by 2020 to meet its target - several thousand more turbines - which is a cause of major concern for anti-wind campaigners.

The new “stealth” turbines features radar absorbing materials (RAM) integrated into the manufacturing processes for the components - blades, nacelle and tower - which cuts the interference they can cause to the point where they can be effectively “factored out” of air traffic control and air defence systems.

The current project has grown out of a multi-million pound scheme, part funded by the government, which ended last year following the trial of stealth blade at North Pickenham, near Swaffham.

“We were told that we had to come up with something that complied with the existing manufacturing process and does not increase the price of the machine by much,” added Dr Moore.

Further trials of the technology are expected to be carried out later this year with the aim of being ready to go into production at the start of next year.

The Ministry of Defence (MOD) has objected to several plans in Norfolk, including a wind farm at sports car manufacturer Lotus's test track at Hethel, because of possible interference to the air defence radar at Trimingham, 32 miles away on the north Norfolk coast.

It later withdrew its objections and the application has since been approved.

According to the British Wind Energy Association, which represents this country's wind and marine renewables industries, the east of England is one of the worst for meeting wind targets.

James Beal, managing director of Renewables East, which is charged with pushing the region's renewables industry forward, said: “Stealth turbines are good news for the wind industry. It unblights an awful lot of the country, although it is only part of the problem solved.

“Although in the last six years we have seen significant wind development, in the last 18 months we have seen virtually nothing and this has been one of the constraints.”

Many anti-wind campaigners said they were waiting to see if the “stealth” technology would be successful in further trials before commenting.

Brian Kidd, chairman of the Campaign Against Turbines at Shipdham and Scarning (CATSS), said: “If it can get rid of the problem then I suppose wind turbines that are held up by objections from the Ministry of Defence and civil airports will go ahead but I suspect they will need to complete a lot more trials to prove its effectiveness.”